Electric pump



March 7, 1939.

. N: c, PRICE 2,149,545

ELECTRIC PUMP Filed Dec. 1, 1937 Naihan attorney Patented Mar. '7, 1939 UNITED STATES ELECTRIC PUMP Nathan C. Price, Seattle, Wash, assignor to Boeing Aircraft Company, Seattle, Wash, a corporation of Washington I Application December 1, 1937!,r Serial No. 177,527 6 claims. (on; 103-53) The present invention is directed to a pump for circulating liquid, particularly in sealed or closed circulating systems, such as are em- .ployed in heating or heat transferring systems upon airplanes. Such a pump is employed or useful, for instance, in the Cabin heating system disclosed in my copending application Serial No. 160,372, filed August 23, 1937, and in mycopending application for a Galley heating system, Serial No. 17,526, filed December 1, 1937.

For use upon airplanes, lightness in weight is an essential, coupledwith ability todelivera suflicient quantity at a required pressure. The pressure requirements may vary considerably between just suflicient to overcome the pressure drop in a circulating system to pressure required to force a liquid through a high pressure series tube boiler. The displacement requirements may likewise vary, as in a galley system, between points of zero or nearly zero displacement when the galley is shut down, to a large or maximum displacement when the galley is operating at full capacity.

A' further requirement for airplane use is reliability and freedom from servicing requirements. a

It is also frequently desirable in airplane installations that the circulating system be sealed, to the end that water or other liquid may not es-v cape, and the pump employed should be, insofar as pos'sible, without any external connections to the plunger whatsoever, so that the liquid may pass through the pump without any possibliity of leakage through packing. A positive displacement pump is preferable in such systems, yet a positive displacement pump generally entails a piston rod which projects through packing, leaving thereby the possibility of escape of liquid .or vapor through the packing. Pulsating diaphragm or autosyn pumps are used in a sealed I system, but are subject to theobjections, among others, that their displacement rate and range,

and their maximum pressure capability, are low.

It is an object of the present invention to devise a displacement pump which will meet the above requirements, for use in such systems as mentioned, or for general use, and which in addition to being simple, completely closed and leak-proof, free from service requirements, and

light, will require a minimum of power to opefate it, which will produce appreciable maximum pressures, which will have a. readily variable capacity, and which may be subject conveniently to automaticcontrol, under the influence of a. change in some physical characteristic of the fluid being pumped, as for instance, its temperature or pressure.

A further object is to provide such a pump which, because it may be necessary to install it in spaces adjacent a passenger compartment, will 5 be quiet, and will operate with the minimum of noise-from reciprocating parts. v

' With these and other objects in mind, as will appear hereafter, my invention comprises the novel pump, and the novel parts and combinationsthereof, as s own in the accompanying drawing, described in this specification, and more particularly defined by the claims which terminate the same.

In the accompanying drawing I have shown my -invention in'a preferred form.

The figure is an axial section through the pump and associated parts, with the control system shown in diagrammatic form.

The fluid is passed in a single direction through a conduit defined in part by the tube 1. At each end this tube is provided with a stop or closure,

as indicated by the plugs l0 and H, having connections at I0 and H, respectively, for inlet and discharge of water. There are noother op- 5 enings into the chamber l2 thus defined, and the fluid being pumped passes through the casing [in the direction indicated by the arrows.

The fluid is advanced by a reciprocable plunger 2 received within' the chamber l2 and reciprocable between limits defined by the plugs I 0 and I l. Suitable means, such as a compression spring 20, seated at one end upon the plug ii and at its other end upon a shoulder within the piston 2, urges the piston toward one limit of its movement as definedby the plug Ill. The piston has a through bore, preferably axially disposed, and indicated at 2|, through which fluid flows between the inlet and discharge ports.

An inlet valve 3 and an outlet valve 3|! control 40 the admission and discharge of fluid and its passage through the pump. The plunger 2 is provided with suitable circumferential sealing grooves, or is otherwise sealed about its periphery within the tubular casing I. The plunger 2 is completely free within the chamber l2, and devoid of any physical external 1 connections. Itis formed of magnetic material, the tube I being of nonmagnetic material, and an electromagnetic coil 4 surrounds the tube l, '50 the closure ll being preferably also of magnetic material, and upon energizing the coil 4 the plunger, 20 is attracted toward the closure ll. opposition to the spring 20 or other force, latent or active, urging it towards the closure II]. If

the plunger will be again brought toward the closure I, thus accomplishing a pumping action.

It is only necessary, therefore, to provide suitable automatic make and break means in the circuit to the coil 4, in order to accomplish a pumping action.

As will now be apparent, the fluid-advancing force may be either the spring's force or the magnetic attraction, or magnetic attraction may be employed to move it in both directions, by. suitable arrangement and alternate energization of electromagnets to this end.

Current from a grounded battery 40 or other power source is fed to the terminal 4| of the coil, preferably through a rheostat 43 or similar device for altering a characteristic of the current, by way of a lead 44. From the opposite terminal 42 of the coil the current is again grounded past a condenser 49 and also through a spring conductor 45 leading to a contact 46 carried upon an arm 5 of insulating material pivoted at 50 upon'the-side of the electromagnet casing, when this contact 46 -makes contact with a complemental contact'point 41 carried upon a grounded conductive arm 5|, which is of magnetic material. A spring 52 urges the arm 50 towards thearm 5, whereby thecontact points 46 and 41 are en-. gaged, but the arm' 5|, upon energization of the electromagnet coil 4,"is attracted toward the latter, thereby breaking contact between 46 and 41, and deenergizing the coil.

The rapidity of the make and break between contacts 46 and 4'! determines the pumping rate of the plunger 2. This pumping rate can therefore be varied byvarying the rate of make and break, and as this is a function of a characteristic of the current it can be varied by means of adjustment of the arm 48 of the rheostat 43 or by means of adjustment of the capacity of the condenser '49. Such adjustment might be manual, but can be controlled automatically, inaccordance with any condition to be controlled,' as by variation in a physical characteristic of the fluid being pumped. For instanc'efla bulb 6 disposed to be influenced byj'the fluid being pumped -may be sensitive to the changein a physical property of the fluid, as for. instance, its temperature or pressure. This bulb 6 being connected through a conduit 5|) to a pressure bellows 6|, and the control system being liquid-filled, rise in temperature of the fluid flowing past the bulb 6 efiects expansion of the liquid and consequent expansion of the bellows 5| therebyshifting the.

pivoted rheostat arm 48, and varying the characteristics of the current supplied to the electro-,

magnet coil- 4.

The arms 5 and 5| are pivoted about the common pivot 50, hence they may move together. When the contact point 41 is in contact with the contact point 48 the circuitthrough the coil. is

completed, and as stated above, the magnetic armature arm 5| is attracted to thecasing 1, and the circuit is broken. As the arm 5| rebounds under the influence of the spring 52, or any equiv-"- alent force, the contact points 41. and 46 again" come together. If the point-4C were solidly fixed in position, the point 41 might rebound therefrom before the coil had become energized. vTherefore,

by supporting the point 48 yieldingly, the two points 41 and remain in contact for an ap- -preciable period,'during rebound of the arm 5| and during return of the two arms as-the armaextension projecting charge, respectively,

electromagnetic 2 coil means to repeatedly energize said ture arm 5| is again attracted towards the casing I and the arm 5 is returned by its spring 45. This contact over an appreciable period assures that the coil 4 will be energized, and prevents chattering or malfunctioning of the pump. It has been found to operate most smoothly when the arm 5| moves to the left of its point of ensagement with the arm 5 about as faras it moves to the right of that point. 1 The periodicity of the pump might be varied by altering the periodicity of one or both of the springs 45 and 52, as by more or less damping of the spring 45, instead of by the rheostat 43 or other electrical means suggested above. The electric control is preferred, however.

The arm 5| is provided with a projection 53, and the magneticcasing I, which surrounds the coil 4, is provided with a pocket 54 of a size and shape to closely receive the projection 53. The projection 53, as it enters the pocket 54, traps air within the pocket, and this serves to cushion and check the advance of the arm 5|, and also to retard somewhat its rebound; acting as a dash-- pot. In addition it acts to stop the movement of the. arm 5| without. noise, and thereby materially quiets the operation of the pump.

' The same cushioning principle may be employed in connection with the reciprocation of the plunger 2. This is provided with a forward projection 23 at one end, and the closure at this end is provided with a pocket l3 to closely receive the projection 4,; and as before, to trap fluid within the pocket, and to act to check the movement of the piston in this direction without appreciable noise. 1 The plunger may be provided with a similar projection at the opposite end, or, as shown, with a recess 24, to receive and to closely embrace a projection H on 'the closure |.|l. The projections 23 and I4 and the corresponding pockets are preferably coaxial with the plunger 2, so that they will seat properly in any rotated position of the plungera What I claim as my invention is:'

1. In combination with a nonmagnetic cylindrical conduit, a closure for each'end thereof, each having a connection for the supply and discharge, respectively, of fluid, "an axially bored plunger of magnetic material loose within and reing said plunger against one such closure, an

electromagnetic coil surrounding the conduit,

and when energized pulling the plunger in the opposite direction, valve meansv to restrict now through the plunger and conduit to a single direction, automatic intermittent make-and-break mea to repeatedly energize said coil, and an axially from an end of the plunger, the closure at such end having a regis-. tering recess closely receiving said projection, to trap liquid as; a cushion to check movement of the plunger. r

.2. In combination with drical conduit, a closure a nonmagnetic cvlinfor each end thereof,

each having a connection for the supply and disof'fluid, an axially bored' plunger of magnetic materialloose. within and reciprocable'lengthwlse of the conduit, means urging saidplunger against one such closure, an'

surrounding the conduit, and when energized pulling the lunger in theopposite direction, valve means to-restrlct flow through the plunger and conduit to a single direction, automatic intermittent make-and coil, and a concentrically disposed means, extending at each end 01' the plunger, theclcsures each having a registering meansto closely flt the corresponding plunger-carried means, one of said complemental means being formed as a projecting tip and the other as a recess, to trap liquid as a cushion to check movement oi the plunger.

3. In combination with a casing defining a closed chamber having only an inlet connection at one end and a discharge connection at its other-end, a free plungerreciprocable lengthwise within said chamber, and having' a through bore, spring means urging said plunger towards one end' of the chamber, an electromagnetic coil surrounding said casing, and when energized urging' said plunger towards the opposite end of the chamber, valve means constraining fluid to flow in one direction. through the chamber and the plungers bore, an armature arm attracted to the electromagnetic coil, upon energimtion or the latter, a spring urging said arm away from the coil, a contact'in the coil circuit carried by said 7 arm, a cooperating contact engageable by the arm's contact upon movement of the arm under the influence oi, the spring, and disengageable upon movement of the am under magneticattractioma tip projecting from the arm, and

a recess closeb' embracing said tip, to trap air and to check the direction.-

.4. A pump comprising a through conduit, an axially'bored plunger oi magnetic material reclprocable within said conduit, an-electromagnet coil surrounding the conduit, and. when energized moving the plunger in'one direction, means to move the plunger in theopposite direction, upon movement of the arm in one deenergization ot the electromagnet coil, an arm oiflmagnetimmaterial disposed externally oi the conduit and carrying a contact 'point in circuit withthe coil, and mountedupon thecoiLtobe,

attractedthereto, spring means urging the arm at all times-away from the coil, and a com-' 'plemental contact in the coil circuit, i po ed to be contacted by the arm's contact only when the arm is moved away from the coil, and yieldably mounted to move with the arm upon their nmemcnt, away iron: the coil under the impetus'oi the spring-urged arm, and towards'the tacted by the arm's-contact when the arm isto closely embracesaid projection, and to check movement of the arm.

the reaction of its 'own' yieldabie mounting when such impetus is spent.

5. A pump comprising a through conduit.- an axially bored plunger 01' magnetic material reciprocable within said. conduit, an electromagnet 5 moved away from the coil, and yieldably mounted to move wlththe arm upon their engagement,

a projection carried upon the arm, and a pocket disposed adjacent the coil, of a size and shape 6. In a pump, in combination, a casing deflning a pump chamber and having valve;controlled inlet and outlet ports, a plunger of magnetic material reciprocable to effect a pumping action through said chamber, an eletic coildispcsedtoattract saidphmgerwhenenergized, to 'eiiect its reciprocation, a pair of contacts in the .electromagnets circui a. separate pivoted arm carrying eachof said contacts and a both concentrically monnted,'spring means urge ing'the first oi saidarms and its contact towards the second arm, and intot with the latters contact, said first arm being of magnetic materialand disposed to' beattracted by the electromagnet, when energised, in opposition to its spring. to break-contact, and a spring acting upon the second arm and yieldahle under impact oithenrst arm,whenthe latter-.isreturnedto contacting position, and by its reaction urging m the second armin the direction oi'movement of the first arm and holding the contacts closed for an appreciable period as the first armis again attractedbyrcenergisationoftheelectromagnet us'rnsn cannon. 

